CHIRP

This is expected (to some people). Ubuntu and many other distros removed python 2.7 so building for focal and later distributions is not possible until the move to python3 is complete.

You can resolve this a few ways

1) Download the windows version and use WINE.
2) Install flatpak, and then add the flatpak hub, then install the flatpak file from https://trac.chirp.danplanet.com/chirp_daily/LATEST/
3) Update your sources.list file to use Xenial (instead of Focal), then find and install the missing dependencies
4) Find all the dependencies sources to compile them and install them.

Regarding # 1, This may be the easiest but I personally don't like the way CHIRP looks in WINE. At least one mailing list member has said this works successfully. I also have verified that past versions do work under WINE.

Regarding # 2, I believe this is the best compromise. You install flatpak once, add the "hub" then install the flatpak file from the command line and you're done.

Here's the instructions for # 2:
Download the .flatpak file from the downloads page mentioned above
In a command terminal, run the following commands:

sudo apt install flatpak
sudo apt install gnome-software-plugin-flatpak
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

If you don't have flatpak installed you should restart your computer. This will let the shortcut icons appear in your cinnamon menu.

Then, depending on the flatpak version, something like

flatpak install $/Downloads/chirp-daily-20200909.flatpak

Just do the last step over again whenever you download a new flatpak file.